An acoustic wave device using a piezoelectric thin film resonator is used for a filter and a duplexer of a wireless device, such as a cellular phone, for example. The piezoelectric film resonator has the structure that a lower electrode and an upper electrode are opposite so as to put a piezoelectric film therebetween.
For example, there are a filter and a duplexer as the acoustic wave device using the piezoelectric thin film resonator. In these acoustic wave devices, a resonance frequency, an anti-resonance frequency or a frequency of a pass band changes by a temperature. There has been known a technique in which a temperature compensation film is provided in a piezoelectric film, as a technique to compensate for the temperature change (e.g. Japanese Patent Application Publication No. 1-48694, and Proc. IEEE Ultrasonics Symposium 2009, pp 859-862)
However, when the temperature compensator film is provided in the piezoelectric film, a resonance characteristic, such as a Q-value and/or an electromechanical coupling coefficient, decreases. When the Q-value decreases, for example, a steep skirt characteristic of the filter and the duplexer decreases.